The present invention relates to a vertically aligned continuous rotary heat exchanger and heat exchanger elememt therefor for the continuous processing of various materials while heating, cooling and stirring such materials.
The present invention is particularly directed to a vertically aligned continuous crystallizer for the crystallization processing of sugar massecuites.
It is known that the crystallization processing of sugar massecuites, i.e. the separation of sugar crystals from molasses, is very delicate and requires accurate temperature control in order to prevent formation of improper grains. Such crystallization processing also requires a progressive and uniform growth of the sugar crystals. In a continuous process, this is possible only if a progressive and uniform decrease in the massecuite temperature is maintained along the length of the crystallizer apparatus during the cooling period. This requires that the cooling fluid circulate in a direction generally opposite to that of the massecuite.
There are known a number of different types of heat exchangers which have been used in the crystallization processing of sugar massecuites. The most preferred of such heat exchangers have been of the type which allow for continuous operation and in which the hot massecuite enters one end of the heat exchanger and moves in a horizontal direction to exit at the opposite end, while the cooling fluid, normally water, circulates horizontally through various tubes or discs mounted on a horizontal rotating shaft in a direction substantially opposite to that of the massecuite.
However, in such horizontal systems it is difficult to achieve uniform flow of the material in the horizontal direction. It is furthermore difficult to obtain uniform flow of the cooling fluid. Finally, such horizontal systems place a very considerable weight on the rotating horizontal shaft which sometimes requires the use of intermediate bearings to prevent undue deflection of the rotating shaft. Such horizontal systems additionally require the use of stuffing boxes.